Field characteristics

Field characteristics

Convection of molten iron within the outer liquid core, along with a  caused by the overall planetary rotation, tends to organize these "electric currents" in rolls aligned along the north-south polar axis. When conducting fluid flows across an existing magnetic field, electric currents are induced, which in turn creates another magnetic field. When this magnetic field reinforces the original magnetic field, is created that sustains itself. This is called the and it explains how the Earth's magnetic field is sustained.

Another feature that distinguishes the magnetically from a bar magnet is its  At large distances from the planet, this dominates the surface magnetic field. Electric currents induced in the  also generate magnetic fields. Such a field is always generated near where the atmosphere is closest to the Sun, causing daily alterations that can deflect surface magnetic fields by as much as one degree. Typical daily variations of field strength are about 25 nanoteslas (nT) (i.e. ~ 1:2,000), with variations over a few seconds of typically around 1 nT (i.e. ~ 1:50,000)

The strength of the field at the Earth's surface ranges from less than  in an area including most of South America and South Africa to over  around the magnetic poles in northern Canada and south of Australia, and in part of Siberia. The average magnetic field strength in the Earth's outer core was measured to be 25 Gauss, 50 times stronger than the magnetic field at the surface.

The field is similar to that of a bar The Earth's magnetic field is mostly caused by in the liquid core. The Earth's core is hotter than 1043 , the  above which the orientations of  within iron become randomized. Such randomization causes the substance to lose its magnetization.